Oil phase polymerization of resins



Patented Apr. 12, 1949 r OFFICE OIL PHASE POLYMERIZATION OF S Charles F. Fisk, Clifton, N. 1., assignor to United. States Rubber Company, New York, N. Y., a corporation of New Jersey No Drawing. ApplicationApril 28, 1944,

Serial No. 533,252

6 Claims. (Cl. zoo-45.4)

This invention relates to improvements in the manufacture of products, and fabricated articles, from certain resins of the general classknown as non-by-product-forming polymerizable resins. These resins are formed of liquid or semi-liquid polymerizable components which polymerize together, or interpolymerize, in what is known as the oil phase, without splitting oif by-products, e. g., water, to form, eventually, hard resins. Usualiy, this reaction is expedited by the use of an oxygen-containing polymerization catalyst such as benzoyl peroxide, peroxides of aliphatic acids, ascaridole, and other organic peroxides, but evenso' temperatures of 50 C. to 125 C. are usually required for rapid gelation and polymerization.

It is the purpose of this invention to provide a practical means for greatly accelerating at temperatures below 50 C. the interpolymerization of unsaturated alkyd resins with monoenic com pounds having a single terminal ethylenic group cm=c The speed with which these known systems polymerize can be regulated within certain limits by regulating the amount of oxygencontaining catalyst added and the temperature at which the polymerization is carried out. It is possible. by such means to prepare systems which will polymerize in afew minutes at the higher temperature, 1. e., 125 C., or in a few hours at the lower temperature, e. g., 50 C. It is also customary to add polymerization inhibitors to the liquid polymerization systems to prevent premature polymerization during storage but this desired storage stability is of necessity accompanied by a decrease in the overall rate at which polymerization takes place in thepresence of the usual catalysts such as benzoyl peroxide. Thus it becomes necessary to use more catalyst to obtain a given rate of polymerization, than would be necessary with an uninhibited polymerization system.

While it is of course possible to accelerate the polymerization of certain systems containing no added inhibitors so that they will polymerize at temperatures below 50 C., in periods of time ranging from a few hours to several days, such an increase in polymerization speed means the sacrifice ofthe storage stability of the uncatalyzed polymerizable system. Such uninhibited systems tend to polymerize spontaneously on standing and to become unstable. Hence this method of increasing the rate of polymerization at temperatures below 50 C. is impractical.

An object of the invention is to provide certain chemical means (called herein promoters),

adJunctive to said oxygen-containing catalyst, for

promoting the gelation and thereby increasing the overall rate of polymerization, at temperatures below 50 0., and thereby giving to the liquid resinous mix cold-setting and cold-curing properties. It will be at once apparent that this permits new and improved fabricating techniques and speeding up of production. Of particular adaptability to this techniqueare the class of resins produced from polymerizable mixtures of unsaturated alkyd resins with mono-enic compounds havin'gflone terminal ethylenic group CHa=C to which belong the resins represented by the polyethylene glycol-maleate-styrene co-' polymer resins, as covered by-the Ellis U. S. Patents Nos. 2,255,313 and 2,195,362. These resins harden to form tough, non-cracking surfaces.

I have found that by using in conjunction with a conventional catalyst, such as benzoyl peroxide, 9. small amount of a promoter which is essentially a sulfhydryl compound, I can greatly increase the overall rate of polymerization at temperatures below 50 C. of polymerizable mixtures of unsaturated alkyd resins with mono-epic compounds having one terminal ethylenic group CH2=C Furthermore, small amounts of these sulfhydryl compounds are effective in increasing the overall speed of polymerization of such polymerizable mixtures containing polymerization inhibitors at temperatures below 50 C. to such an extent that such systems can be polymerized in a few minutes. This rapid rate of polymerization isgalned without any accompanyingsacriflce in the "storage stability of the polymerizable systems. Rapid polymerizations at low temperatures are thus made completely practical.

Polymerizable systems of the type'to which my invention is applicable are commonly used inthe fabrication of laminated articles composed of absorptive or porous sheet materials such as paper, cloth or fibrous glass impregnated with and bonded together with the solid polymer. In preparing these articles it is customary to impregnate or coat the porous sheet material with the liquid polymerizable mixture which has been prepared by known methods, so that it has the proper viscosity at thetemperatures employed during application-dsually about 25 C., or slightly higher. The impregnated sheet materials may then be plied together and formed to the desired shape.

. Heat is then applied to raise the temperature of Whlleitisnecessarytoraisethetemperature to speed up the polymerization of the mixture, this increase in temperature brings about an undesirable decrease in the viscosity of the liquid mixture, flow away from spaces between the layers of fabric or paper leaving so-called starved spots" or areas where there will be insuiiicient polymer in the finished article. This is also true in vertical areas. Dii'iiculty has also been encountered in forming smooth surfaces on flat gsheets with such resins.

n the other hand, by using a polymerizable mixture containing a catalystv and a suiiicient amount of a sulfhydryl compound to cause rapid polymerization at temperatures below about 50 C., it is not necessary to raise the temperature above 50 C. in order to cause the mixture to set to a non-fiowable state. Low-viscosity effects are thus avoided. It is thuspossible to allow the mixture to set or gel at room temperature or slightly above and then, if desired, to complete the polymerization at an elevated temperature without causing unequal distribution of the resin (formation of starved area), since no decrease in viscosity will take place. 1

While the principles of my invention are particularly useful in the production of laminated articles, they can be satisfactorily applied to the production of castings or coatings wherever it is desired to have rapid polymerization at low temperatures. v

The polymerization of the systems involved in this invention takes place in several recognizable stages. The resin mixture remains quite fluid with little or no change in viscosity during a period of time called the inductionhperiod. After this the viscosity increases very rapidly until the material becomes a soft solid. The time to reach this stage is called'the gel time." The material, if undisturbed, continues to increase in hardness until a hard solid stage is reached.

In cm'rying out polymerizations in the oil phase, according to this invention, several procedures may be followed. It is preferred to dissolve the peroxide catalyst in the-less viscous of the inhibited resin components, which is then mixed carefully with the other resin component. The promoter, that is, the sulfhydrylcompound, may then be-incorporated (shortly prior to carrying out the polymerization) directly in the mixture of resin components, catalyst, and inhibitor. The mixture is then ready for use in casting or for producing any such articles as are desired. (It

' has not been found practical to add the promoter to either of the resin components at a time long before use since the activity of the promoter is gradually destroyed on standing.)

If a casting is to be made, the mixture is poured into a previously prepared form and allowed to stand at temperatures ranging from 0 to 50" C. until the resin has polymerized at least to the gel point. If the resin is to be used for impregnating or coating, it is applied to the desired base material and may either be molded immediately and the gel allowed to form in the position desired, or the gel may be allowed to form in a horizontal ,position after which the article can be molded and the rest of the polymerization carried out at a higher temperature.

The base material, subject to impregnating or coating, may be in sheet, filament, or other form, and comprise materials of metal, vegetable, animal, mineral, or synthetic nature.

with the result that the liquid tends tov 4 tionare those which are capable of addition polymerization and contain one and only one terminal OH: group doubly bonded to a carbon atom which in turn is bonded to at least one negative radical. Specific examples of such compounds are styrene in which the negative group is a phenyl radical, vinyl chloride in which it is the chloride radical, vinyl acetate in which it is the aceto'xy radical, esters of acrylic and metQcrylic acids in which it is a carbo-ester radical, newlonitrile and methacrylonitrile in which it is the carbonitrile radical.

The unsaturated alkyds used in the invention are prepared in known manner by the reaction of polyhydric alcohols with cafi-ethylenic dicarboxylic acids with or without the presence of modifying agents, such as monohydric alcohols, satura monocarboxylic acids, saturated polycarboxyl acids, drying or semi-drying oils, etc. Unsaturated alkyds of this type are described in U. 8, Patents Nos. 2,195,362 and 2,255,313.

The proportion in which the interpolymerizable components are mixed may be varied widely, e. g., the amount of the polyenie component, i. e., the unsaturated alkyd resin, may range from about 20% to about of the mixture of .interpolymerizable components.

The following are examples of suitable sulfhydryl compounds: hydrogen sulfide, ammonium hydrosuliide, sodium hydrosuliide, calcium hydrosulflde, n-hexyl mercaptan, n-heptyl mercaptan, n-octyl mercaptan, n-nonyl mercaptan, n-decyl mereaptan, n-undecyl mercaptan, ndodecyl mercaptan, n-tridecyl mercaptan, n-tetradecyl merss captan, n-hexadecyl mercaptan, secondary hexyl mercaptan, tertiary hexyl mercaptan, tertiary octyl mercaptan, mercaptoacetic acid (HS-CHaCOOH) thioacetic acid (CHLCOSH), p-toluenethiol, p-

mercaptophenol, z-mercaptobenzoic acid, 4- mercaptoquinazoline, thio-a-toluamide, thioacetamide, thioacetanilide, Z-naphthalenethiol. cysteinc hydrochloride. thiourea, trithiocyanuric acid, thiohydantoin, thiobarbituric acid.

The amount of promoter may be varied, depending on the specific character or the polymerlzable resin, the specific catalyst, and the speciiic inhibitor. For any given system of inhibited polymerizable resinous mix, it will be found that as the amount of added promoter is increased, the gelling time is progressively reduced until it reaches a minimum, after which further amounts of the promoter provide an operative but less pronounced decrease in the gelling time, compared with control containing no added promoter. Generally, a usable range for the promoter ranges from .005 to 2.0 parts per parts by weight of the liquid polymerizable mixture.

The following examples are given to further 11- lustrate the invention, the parts being by weight:

EXAMPLEI A reactive alkyd is prepared by reacting 1.05 mols or diethylene glycol with 1.00 mol of maleic anhydride (the use of the anhydrlde is equivalent to the use of the acid) at C. in a carbon dioxide atmosphere until an acid number of 50 is attained. Two parts of benzoyl peroxide are dissolved in 30 parts of monomeric styrene containing 0.010 part of p-tertiary-butyl catechol (inhibitor). Seventy parts of the alkyd are then dissolved in the styrene solution by stirring. As soon as this mixture is homogeneous, 0.1 part of The mono-enic compounds used in the inven- 7 dodecyl mercaptan is added and the compound stirred for one minute. The comparative times in which gelation occurred are noted in Table I for the above compound, and tor a compound to which benzoyl peroxide but no mercaptan is added, and for one to which neither mercaptan This example illustrates clearly the tremendous effect obtained by the use of the combination of mercaptan with the peroxide catalyst in the inhibited resin combination.

EXAMPLE II Table II lists the gel times which were observed with numerous promoters used in accordance with the invention. The amount or promoter indicated in the table was added to the resin combination consisting of 70 parts of a. reactive alkyd produced by the condensation of a polyhydroxy alcohol with an ,fi-ethylenic dicarboxylic acid, 30 parts 01' monomeric styrene, 0.01 part of tertiary-butyl catechol and 2 parts oi benzoyl peroxide in the manner described above.

Tuna II cogc' l tlo o 1 Tim er e e. Pmmt Parts Min. at 25C.

Resin) None 3, 000 Hydrogen sulfide gas. bubbled in 30 Sodium hydrosulilde- 2. 0 60 n-Hexyl mercaptam- 0. 2 47 n-Heptyl mercaptan. 0. 2 35 n-Octyl mercaptan.-. 0. 2 l0 n-Nonyl mercaptan 0. 2 122 n-Decyl mcrcaptam- 0. 02 20 n-Undecyl mereaptan 0. 2 119 n-Dodecyl mercaptan 0. 02 30 n-Tridecyl mercaptan... 0. 02 80 n-Tetradeeyl mercaptan 0. 02 20 n-Hexadecyl merca tan. 0. 02 70 Mercaptoacetie aci 2. 0 8 Do 0. 2 10 Do 0. 02 23 Thiourea 0. 02 127 Thiohydantom 0. 02 150 Do 0. 2 180 Trithioc anuric acid- 2. 0 120 Tbiobar ituric acid. 0. 2 180 Benzenethiol. 0. 2 120 D0 0. 02 25 p-Toluenethiol. 0. 2 55 Do 0. 02 p-Mercapto benol 0. 2 15 2-Mercapto nzoic acid 2. 0 15 Do 0. 2 75 Do 0. 02 90 Sec. hexyl mercaptan 0. 02 48 Tert. hexyl mercaptan- 0. 02 35 Tort. octyl mercaptan 0.02 25 EXAMPLEII'II The results of further examples of this invention are recorded in Table III. Two parts of henzoyl peroxide are added'to a polymerizable mix a. eflect oi the'promoter on the speed with which the resin gelled in the presence of a variety of inhibitors.

Tun III Gel Times ilt 25 C.

Inhibitor (0.01 Part) .05 pt.

- dodecyl No promermoter captain Min. Min. tbutyl catecbol- 28 900 hydrog uinone 11 720 tetrac oroquinone.. 18 720 gggnyl p-nalahthylemine. ii 136 zaldehy e i0 52 none. 8 42 Examples of diiterent monoenic monomers having one terminal OH: group and which can be used with the unsaturated reactive alkyd according to the invention are recorded in Table IV. Thirty parts of each monomer are mixed with '70 parts of the reactive alkyd and 2 parts oi benzoyl peroxide with 0.05 part of dodecyl mercaptan are added. The table lists the gel times of the mixtures and shows that the polymerization of all of these mixtures is eil'ected rapidly'by means of the combination of the mercaptan and the peroxide.

of a reactive alkyd of Example I and styrene.

TABLE IV Gel Times at 25 C.

30 flats Monomer .05 pt.

dodecyl No Promercapmoter tan Mn. Jilin. Methil acrylate 78 1,140 Cyclo exyl acrylate-. 12) 720 Methyl methacrylate. 4, 020 Vinyl acetate l, 020 Acrylonitrile 28. 3, 300 Styrene 8 42 EXAMPLE V Table V illustrates the use of different peroxides i that the different peroxides are effective in this system.

'IAnLn V Activity of Diflerent Peroxides: Gel Times at 25 C.

I Dodecyl mercaptan added 0.1 Part None Benzoyl Peroxide 12 minutes.... 12 hours Lauroyl Peroxide 40 minutes. 12 hours Tert.-butyl hydroperoxide 240 minutes... 6 days While I have shown and described various embodiments oi the invention, it is to be understood that the .invention is susceptible to those modiclaim tion promoter.

7 iications which appear within the spirit oi the invention and the scope of the appended claims. Having thus described my invention, what I and desire to protect by Letters Patent is: 1. In a method of controlling theoil phase gelling and polymerization of, a,polymerizable mix comprising a liquid polyenic polyester of a Polyhydric alcohol with an alpha-oleiinic dicarboxylic acid, and a liquid monomeric unsaturated polymerizable compound in which the unsaturation is due to a single terminal ethylenic group which is attached to a negative radical. and in which said ester is soluble and with which ester it is copolymerizable in the presence of a peroiw polymerization cataylst, said catalyst also being present. that improvement which consists in the step adding to said system a small but effective amount of a promoter of gelation which isessentially a,.sulihydryl compound and which is the sole promoter of gelation.

2. In a method of controlling the oil phase gelling and polymerization of a polymerizahle mix comprising a liquid polyenic polyester of apolyhydric alcohol with an alpha-oleiinic dicarboxylie acid, and a liquid monomeric unsaturated polymerizable compound in which the unsaturation is due to a single terminal ethylenic group which is attached to a negative radical, and in which said ester is soluble and with which ester it is copolymerizable in the presence of a peroxy polymerization catalyst, said catalyst also being present, that improvement which consists in the step of adding to said system a small but eilective amount of a hydrocarbonthiol as a gela- 3. In a method of controlling the oil phase gelling and polymerization of a polymerizable mix comprising a liquid polyenic polyester 0! a polyhydric alcohol with an alpha-oleflnie di- 'carboxylic acid, and a liquid monomeric unsaturated polymerizable compound in which the unsaturation is due to a single terminal ethylenic group which is attached to a negative radical, and in which said ester is soluble and with which ester it,is copolymerizable in the presence of a peroxy polymerization catalyst, said catalyst also being present, that improvement which consists in the step of adding to said system a small but eflective amount of n-dodecyl mercaptan as a gelation promoter.

4. In a .method of controlling the oil phase gelling and polymerization of a polymerizable mix comprising a liquid polyhydric alcohol ester of an alpha-oleiinic dicarboxylic acid, and a liquid 'monomeric unsaturated polymerizable compound negative radical, and in which said ester is soluble and with which ester it is copolymerizable in the presence of a peroxy polymerization cataylst. said catalyst also being present, that improvement which consists'in the step of adding to said system a small but effective amount of ammonium hydrosulflde as a gelation promoter.

5. A polymerizable mixture comprising a reactive unsaturated alkyd resin derived from an ethylene-alpha, beta-dicarboxylic acid and a glycol, together with a liquid monomeric unsaturated polymerizable compound in which the unsaturation is due to a single terminal ethylenic linkage CH1==C whichis attached to a negative radical, and in which liquid compound said alkyd is soluble and with which it is copolymerizable in the presence of a peroxidic polymerization catalyst, a peroxidic polymerization .cataylst, and a small but effective amount of a promoter of gelation which is essentially a sulfhydryl compound and which is the sole promoter of gelation.

6. A polymerizable mixture comprising a liquid reactive unsaturated glycol ester of an ethylenealpha, beta-dicarboxylic acid, and a liquid monomeric unsaturated polymerizable compound in which the unsaturation is due to a single terminal ethylenic group which is attached to a negative radical, and in which the said liquid ester is soluble and with which ester it is copolymerizable in the presence of a peroxy polymerization cat"- lyst, and in which the said ester ranges fro. l 20-95% of the mixture of interpolymerlzable components, a peroxidic polymerization catalyst, and a small but effective amount of a promoter of gelation which is essentially a sulihydryl compound and which is the sole promoter of gelation.

CHARLES F. FISK.

BEFEBENOES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS 

